I think it could be of use to you to see a therapist if you are not already doing that.

My belief is that we can support folks and be there for them but ultimately it's up to them to reach a point to help themselves in the ways they see best. Therapy could help you learn to also deal with the impact your daughters potential illness and your husbands has on you, what you can/can not do about it. Also it may be a resource to help you to help your husband in addition to the ideas given here.